Freeze-dried purple cabbage meal replacement cereal strips and preparation method thereof

Abstract

The invention discloses freeze-dried purple cabbage meal replacement cereal strips and a preparation method thereof, and belongs to the technical field of purple cabbage food preparation. The purple cabbage biscuit comprises 30-50 parts of purple cabbage powder, 20-30 parts of glutinous rice, 30-45 parts of oatmeal, 5-16 parts of Chinese wolfberry fruits, 10-20 parts of nuts, 5-10 parts of white granulated sugar and 10-20 parts of malt syrup. The freeze-dried purple cabbage meal replacement grain strips are obtained through raw material screening, cleaning, cooking, compounding, mixing, injection molding, pre-freezing, demolding, freeze drying and packaging. A low-temperature vacuum freeze-drying technology is adopted, several raw materials rich in nutrient substance content are combined and synergistically play a role, the unique flavor and color of purple cabbages are reserved, and the purple cabbage biscuit is rich in anthocyanin, dietary fibers and various vitamins, high in nutritional value, convenient to carry and eat and capable of meeting the fast-paced life requirements of modern people.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of purple cabbage food preparation, and particularly relates to a freeze-dried purple cabbage meal replacement cereal bar and a preparation method thereof. BACKGROUND

[0002] Purple cabbage (Brassica oleracea var. capitata rubra) is easy to grow, cold-resistant, rich in anthocyanins, glucosinolates, vitamins, dietary fiber and other nutrients, and has various biological activities, and is deeply loved by people. At present, purple cabbage is often consumed in the form of fresh food and pickling, and has the disadvantages of poor storage, short shelf life, and single form. The edible form can be changed and the product type can be enriched by compounding with other food materials and food processing technology, and the shelf life can be prolonged.

[0003] At present, there are few related leisure and meal replacement foods with purple cabbage as the main ingredient on the market. In order to meet the increasingly diversified consumer demand of the public, a series of convenient purple cabbage products suitable for people with fast-paced life and having dietary nutrition can be developed according to the nutritional and flavor characteristics of purple cabbage.

[0004] Cereal bars are increasingly popular as a leisure food and meal replacement food, but traditional processes such as baking or extrusion, puffing have the disadvantages of complex process, serious loss of active ingredients, poor taste and flavor, etc. In contrast, vacuum freeze-drying technology can effectively maintain the color, aroma, taste and shape of agricultural products, and can maximize the retention of active ingredients and flavor of products, and has been widely used in fruit and vegetable product processing, which can meet the dual requirements of convenience and nutrition of consumers.

[0005] Therefore, the present application proposes a freeze-dried purple cabbage meal replacement cereal bar with higher nutritional value. SUMMARY

[0006] To solve the above technical problems, the present application proposes a freeze-dried purple cabbage meal replacement cereal bar and a preparation method thereof, which are used to solve the problems of single product, low nutritional value and inconvenience of carrying out of the current meal replacement cereal bar products.

[0007] The present application realizes the above-mentioned purpose through the following technical scheme, a freeze-dried purple cabbage meal replacement cereal bar and a preparation method thereof, the raw materials of which include, by weight: 30-50 parts of purple cabbage powder, 20-30 parts of glutinous rice, 30-45 parts of oatmeal, 5-16 parts of wolfberry, 10-20 parts of nuts, 5-10 parts of white granulated sugar, and 10-20 parts of malt syrup. Further, the glutinous rice and oatmeal are soaked and cooked, then the purple cabbage powder, nuts and wolfberry are added and mixed uniformly, cooled and injected into a mold for pre-freezing and forming, demolded after pre-freezing, and placed in a freeze-drying tray for vacuum freeze-drying to obtain the freeze-dried purple cabbage meal replacement cereal bar.

[0008] Further, the glutinous rice is kneaded, washed and dried in clean water, and then is boiled in a pot with water.

[0009] Further, the oatmeal is steamed in a pot and is ready for use.

[0010] Further, the purple cabbage powder is mixed with nuts and wolfberry, and is ready for use.

[0011] Further, the white granulated sugar and malt syrup are mixed and heated to obtain mixed malt syrup.

[0012] Further, the glutinous rice and oatmeal are steamed, and then are mixed with the purple cabbage powder, nuts, wolfberry and mixed malt syrup to obtain a mixture after cooling.

[0013] Further, the mixture is poured into a pre-prepared mold, and is pre-frozen for 4 hours at-20℃ to-25℃ to form a shape. During the injection molding process, the mixture is ensured to fill the mold, and the mold is gently shaken or tapped to remove air bubbles.

[0014] Further, after the mixture is completely frozen, the mold is removed, and the mixture is quickly demolded at-18℃. During the demolding process, the mixture is gently tapped around the mold to separate the mixture from the mold wall, and the mold is inverted on a flat workbench, and the mixture is gently tapped from the bottom of the mold to make the mixture come out of the mold. The appearance and texture of the mixture are checked to ensure that the mixture is not left in the mold.

[0015] Further, the shaped mixture is vacuum dried after being frozen at-30℃ for 2 to 3 hours, the cold trap temperature is-35℃ to-45℃, the vacuum degree is less than or equal to 100 Pa, the baffle temperature is dried at 45℃ for 4 hours and at 65℃ for 12 hours.

[0016] The application also provides a freeze-dried purple cabbage meal replacement cereal bar prepared by the preparation method.

[0017] Compared with the prior art, the application has the following advantages and technical effects:

[0018] (1) The application uses a specific vacuum freeze-drying technology to combine glutinous rice, oatmeal, purple cabbage powder and wolfberry, which are rich in nutrients, to play a synergistic role. Not only is the release and transformation of beneficial ingredients in the purple cabbage achieved, but also the nutritional ingredients in the raw materials are preserved by using the vacuum freeze-drying technology. The product produced is more stable, uniform and has excellent functional effects. The freshness, taste and shelf life of the product are improved while the nutritional ingredients are preserved, and efficient preparation is achieved.

[0019] (2) The freeze-dried purple cabbage meal replacement cereal bars prepared by the present invention are small and convenient to eat. They do not require the addition of chemical additives. They not only meet the needs of people who are trying to lose weight for low-energy nutritionally balanced foods, but also focus on the balanced supplementation of other nutrients, thus meeting the existing market demand for green and healthy foods. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation process of the freeze-dried purple cabbage meal replacement cereal bars of the present invention.

[0021] Figure 2 This is a product image of the freeze-dried purple cabbage meal replacement cereal bars of the present invention;

[0022] Figure 3 This is the total sugar standard curve of the present invention;

[0023] Figure 4 This is the ascorbic acid standard curve of the present invention;

[0024] Figure 5 This is the standard curve of gallic acid according to the present invention;

[0025] Figure 6 This is the result of the acid value change of the freeze-dried purple cabbage meal replacement cereal bars of the present invention during storage at room temperature;

[0026] Figure 7 This is the result of the change in peroxide value of the freeze-dried purple cabbage meal replacement cereal bars of the present invention during storage at room temperature. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The raw materials used in the preferred embodiments of this invention are all commercially available.

[0029] The process flow diagram for preparing the freeze-dried purple cabbage meal replacement cereal bars of this invention is shown below. Figure 1 .

[0030] This invention also provides a freeze-dried purple cabbage meal replacement cereal bar prepared by the above method. A product image is shown below. Figure 2 .

[0031] The technical solution of the present invention will be further illustrated by the following embodiments.

[0032] Example 1:

[0033] Preparation of freeze-dried purple cabbage meal replacement cereal bars:

[0034] (1) Wash and dry 200g of glutinous rice in clean water, add water and pour into a pot, cook at 90℃ for 40 minutes, and set aside.

[0035] (2) Add 150g of oatmeal to water and pour it into a pot. Cook at 85℃ for 18 minutes. Set aside.

[0036] (3) Mix 200g of purple cabbage powder and 30g of nuts with 40, 45, 50, 55 and 60g of goji berries respectively, and set aside.

[0037] (4) Mix 25g of white sugar and 50g of malt syrup in a ratio of 1:2 and heat to 80°C to obtain mixed malt syrup.

[0038] (5) The glutinous rice and oats obtained from the above steaming and cooking process are mixed with purple cabbage powder, nuts, goji berries and mixed malt syrup, and then cooled to obtain a mixture.

[0039] (6) Pour the mixture into the prepared mold and pre-freeze at -23°C for 4 hours to allow it to solidify. During the injection molding process, ensure that the mixture fills the mold completely and gently vibrate or tap the mold to remove air bubbles.

[0040] (7) After the mixture has been pre-frozen and solidified completely, remove the mold and demold quickly at -18℃. When demolding, gently tap the sides of the mold to allow the mixture to detach from the mold wall. Invert the mold onto a flat workbench and gently tap the bottom of the mold to allow the mixture to come out of the mold. Check the appearance and texture of the mixture to ensure that there is no residue left in the mold.

[0041] (8) The shaped mixture is frozen at -30℃ for 3 hours and then vacuum dried. The cold trap temperature is -35℃, the vacuum degree is ≤100Pa, and the partition temperature is 45℃ for 4 hours and 65℃ for 12 hours.

[0042] Example 2:

[0043] Preparation of freeze-dried purple cabbage meal replacement cereal bars:

[0044] (1) Wash and dry 200g of glutinous rice in clean water, add water and pour into a pot, cook at 90℃ for 40 minutes, and set aside.

[0045] (2) Add water to 100, 115, 130, 145 and 160g of oatmeal respectively and pour them into a pot. Cook at 85℃ for 18 minutes and set aside.

[0046] (3) Mix 200g purple cabbage powder, 30g nuts and 50g goji berries and set aside.

[0047] (4) Mix 25g of white sugar and 50g of malt syrup in a ratio of 1:2 and heat to 80°C to obtain mixed malt syrup.

[0048] (5) The glutinous rice and oats obtained from the above steaming and cooking process are mixed with purple cabbage powder, nuts, goji berries and mixed malt syrup, and then cooled to obtain a mixture.

[0049] (6) Pour the mixture into the prepared mold and pre-freeze at -23°C for 4 hours to allow it to solidify. During the injection molding process, ensure that the mixture fills the mold completely and gently vibrate or tap the mold to remove air bubbles.

[0050] (7) After the mixture has been pre-frozen and solidified completely, remove the mold and demold quickly at -18℃. When demolding, gently tap the sides of the mold to allow the mixture to detach from the mold wall. Invert the mold onto a flat workbench and gently tap the bottom of the mold to allow the mixture to come out of the mold. Check the appearance and texture of the mixture to ensure that there is no residue left in the mold.

[0051] (8) The shaped mixture is frozen at -30℃ for 3 hours and then vacuum dried. The cold trap temperature is -35℃, the vacuum degree is ≤100Pa, and the partition temperature is 45℃ for 4 hours and 65℃ for 12 hours.

[0052] Example 3:

[0053] Preparation of freeze-dried purple cabbage meal replacement cereal bars:

[0054] (1) Wash and dry 160, 180, 200, 220, 240 and 260g of glutinous rice in clean water, add water and pour into a pot, cook at 90℃ for 40 minutes, and set aside.

[0055] (2) Add water to 100, 115, 130, 145 and 160g of oatmeal respectively and pour them into a pot. Cook at 85℃ for 18 minutes and set aside.

[0056] (3) Mix 200g purple cabbage powder, 30g nuts and 50g goji berries and set aside.

[0057] (4) Mix 25g of white sugar and 50g of malt syrup in a ratio of 1:2 and heat to 80°C to obtain mixed malt syrup.

[0058] (5) The glutinous rice and oats obtained from the above steaming and cooking process are mixed with purple cabbage powder, nuts, goji berries and mixed malt syrup, and then cooled to obtain a mixture.

[0059] (6) Pour the mixture into the prepared mold and pre-freeze at -23°C for 4 hours to allow it to solidify. During the injection molding process, ensure that the mixture fills the mold completely and gently vibrate or tap the mold to remove air bubbles.

[0060] (7) After the mixture has been pre-frozen and solidified completely, remove the mold and demold quickly at -18℃. When demolding, gently tap the sides of the mold to allow the mixture to detach from the mold wall. Invert the mold onto a flat workbench and gently tap the bottom of the mold to allow the mixture to come out of the mold. Check the appearance and texture of the mixture to ensure that there is no residue left in the mold.

[0061] (8) The shaped mixture is frozen at -30℃ for 3 hours and then vacuum dried. The cold trap temperature is -35℃, the vacuum degree is ≤100Pa, and the partition temperature is 45℃ for 4 hours and 65℃ for 12 hours.

[0062] Table 1 Sensory Evaluation Table

[0063]

[0064] Orthogonal experiments were conducted based on Examples 1-3:

[0065] Based on the results of the single-factor experiments, an orthogonal experimental design was used to determine the optimal preparation conditions. The amounts of wolfberry (A), oat flakes (B), and glutinous rice (C) were selected as three factors, with three levels for each factor. An L9(33) orthogonal experiment was conducted, using the sensory evaluation of the freeze-dried purple cabbage meal replacement cereal bars as the evaluation index to determine the optimal preparation conditions. The orthogonal experimental design is shown in Tables 2 and 3.

[0066] Table 2 Factors and Levels in Orthogonal Experiment

[0067]

[0068] Table 3 Orthogonal Experimental Design Table

[0069]

[0070] The orthogonal experimental analysis is shown in Table 4.

[0071] Table 4 Orthogonal Analysis Table

[0072]

[0073] Based on the results of single-factor experiments, the main factors affecting the preparation conditions—the amount of goji berries, oat flakes, and glutinous rice added—were selected as independent variables, and sensory scores were used as the dependent variable in an orthogonal experiment to optimize the preparation process. Table 4 shows that the order of importance of the three factors affecting the sensory score of freeze-dried purple cabbage meal replacement cereal bars is A, B > C, namely, the amount of goji berries added, the amount of oat flakes added, and the amount of glutinous rice added. The experimental results indicate that the optimal factor combination is A2B2C3, i.e., 50g of goji berries, 130g of oat flakes added, and 220g of glutinous rice added. Under these conditions, the sensory score of the freeze-dried purple cabbage meal replacement cereal bars is 90 points.

[0074] The following indicators were measured on the freeze-dried purple cabbage meal replacement cereal bars prepared in Examples 1-3:

[0075] (1) Moisture content determination: Label the dried glass weighing dish and record the weight as m3. Take a sample of 3-5g, spread the freeze-dried purple cabbage meal replacement cereal strips evenly on the glass weighing dish, and record the weight as m1. Place the weighed sample in a 95-105℃ electric thermostatic drying oven, weigh it every 2 hours, and remove it after constant weight, recording the weight as m2. Formula:

[0076] W = (m1 - m2) / m1 × 100%

[0077] The moisture content results are shown in Table 5. As can be seen from Table 5, the moisture content of the freeze-dried purple cabbage meal replacement cereal bars is 3.16%.

[0078] It complies with the standards stipulated in GB7099~2015 "National Food Safety Standard for Pastries and Bread" and GB / T20977~2007 "General Rules for Pastries". The blended purple cabbage mixture is easier to shape and has a thinner overall thickness than the unblended mixture. This shortens the distance heat travels from the surface to the center of the food, and also reduces the distance moisture travels from the interior to the surface to escape. Secondly, to prevent the freeze-dried purple cabbage meal replacement cereal bars from absorbing moisture, they should be promptly packed into aluminum foil bags and sealed for storage.

[0079] Table 5. Results of various indicators of freeze-dried purple cabbage meal replacement cereal bars

[0080]

[0081] (2) Determination of hardness and brittleness: A P50 cylindrical probe was selected for the texture analyzer. The freeze-dried purple cabbage meal replacement cereal strips were placed directly under the cylindrical probe to measure their hardness and brittleness. Parallel measurements were taken. Pre-test speed: 3.00 mm / sec; during test: 2.00 mm / sec; post-test speed: 3.00 mm / sec; strain: 30%; time: 5.00 sec; trigger force: 5 g. Each sample was tested 3 times and the average value was taken.

[0082] The results of hardness and brittleness are shown in Table 5. Table 5 shows that the hardness of the freeze-dried purple cabbage meal replacement cereal bars is 0.82 N, and the brittleness is 0.171 N. The freeze-dried purple cabbage meal replacement cereal bars are weak in withstanding external forces and are relatively brittle. They should be protected from compression as they are easily broken. Increasing the drying temperature can appropriately improve the brittleness of the freeze-dried purple cabbage meal replacement cereal bars. Additionally, the added sugars in the ingredients also have a certain impact on the hardness and brittleness of the freeze-dried purple cabbage meal replacement cereal bars.

[0083] (3) Color measurement: The color difference of freeze-dried purple cabbage meal replacement cereal bars was measured by a fully automatic colorimeter and calibrated before use.

[0084] Freeze-dried purple cabbage meal replacement cereal bars should have a color corresponding to their raw materials, as color is one of the main indicators of the crispness of fruits and vegetables. The smaller the L* value, the more severe the browning. Studies have shown that the L* value is related to the browning of fruits and vegetables.

[0085] The color measurement results are shown in Table 6. Table 6 shows that the drying process reduces the brightness of the purple cabbage, resulting in a decrease in the L* value of the freeze-dried purple cabbage. To prevent browning, the samples should be sealed in appropriate packaging bags. The a* value of the freeze-dried purple cabbage meal replacement cereal bars is more reddish than that of the single product. Influenced by the color of goji berries, the single product appears light blue, while both are darker in color. The freeze-dried purple cabbage meal replacement cereal bars have a color closer to the original color of purple cabbage and a richer visual appeal.

[0086] Table 6. Color determination of freeze-dried purple cabbage meal replacement cereal bars

[0087]

[0088] (4) Determination of total sugar

[0089] Grind the sample into powder, sieve it, and pack it into an aluminum foil bag.

[0090] ① Construction of standard curve

[0091] Accurately measure 0 mL, 0.05 mL, 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL, and 0.5 mL of 1 mg / mL glucose stock solution into dry test tubes. Add water to each tube to a final volume of 1 mL, then add 5 mL of colorimetric reagent. Mix well and place in a boiling water bath for 30 min. After cooling to room temperature, measure the absorbance at 490 nm and plot a standard curve. The equation of the standard curve is obtained as y = 0.0082x - 0.0086(R²). 2 =0.9996) Figure 3 As shown.

[0092] ② Preparation of total sugar extract

[0093] Dissolve 0.5g of freeze-dried purple cabbage meal replacement cereal strips in 15mL of water, add 6mol / L hydrochloric acid solution and mix well. Incubate in a boiling water bath for 30min, then remove and cool. Neutralize with 6mol / L sodium hydroxide, transfer the solution to a 100mL volumetric flask using a glass beaker, and dilute to volume with water. Filter the solution from the volumetric flask, take 1mL and dilute to 10mL with water to obtain the total sugar extract.

[0094] ③ Sample measurement

[0095] Take two test tubes and number them. Tube 1 serves as the blank control, and tube 2 is used for total sugar determination. Add reagents to the standard curve and measure the OD value of each tube multiple times at a wavelength of 540 nm, recording the data.

[0096] Because each glycosidic bond broken during the hydrolysis of polysaccharides into monosaccharides adds one water molecule, the polysaccharide content should be multiplied by 0.9 when calculating the polysaccharide content. The total sugar content has a certain impact on the sensory quality, texture, nutritional value, and cost of the product.

[0097] The total sugar content results are shown in Table 7. As can be seen from Table 7, the sugar content of freeze-dried purple cabbage meal replacement cereal bars is close to that of sandwich energy bars. The majority of the sugar in freeze-dried purple cabbage meal replacement cereal bars comes from the auxiliary ingredients. The sugar content of freeze-dried purple cabbage meal replacement cereal bars is lower than that of sweet snack foods, and the taste of freeze-dried purple cabbage meal replacement cereal bars is richer than that of single cereal bars.

[0098] Table 7. Determination of Total Sugar in Freeze-Dried Purple Cabbage Meal Replacement Cereal Bars

[0099]

[0100] (5) Determination of Vitamin C

[0101] ① Construction of standard curve

[0102] Accurately weigh 0.01 g of ascorbic acid, dissolve it in 2 mL of 10% hydrochloric acid solution, and dilute to 100 mL with distilled water to obtain a 100 μg / mL ascorbic acid solution. Take eight test tubes and number them. Add 100 mL, 50 mL, 25 mL, 12.5 mL, 10 mL, 6.25 mL, and 5 mL of 0.5 mol / L NaCl solvent to each test tube, respectively, to obtain solutions with vitamin C concentrations of 1 g / mL, 2 g / mL, 4 g / mL, 8 g / mL, 10 g / mL, 16 g / mL, and 20 g / mL. Take eight colorimetric tubes and number them 0 to 7. Add 5 mL of the diluted solution to each colorimetric tube. Add 5 mL of 0.5 mol / L NaCl to tube 0 as a control. Measure the absorbance of the eight colorimetric tubes at 243 nm using a UV spectrophotometer. A standard curve for the vitamin C standard solution is established using the measured absorbance value as the X-axis and the concentration of the standard vitamin C solution as the Y-axis, as follows:Figure 4 .

[0103] ② Preparation of sample extract

[0104] Take 1g of sample powder, add 5mL of 10% hydrochloric acid, then add another 5mL, mix well to form a homogenate, transfer to a 25mL volumetric flask, and dilute to the mark. Transfer the sample to a centrifuge tube and centrifuge at 3000r / min for 10min. Take the supernatant, which is the test extract for each group.

[0105] ③ Measurement of absorbance

[0106] Take 0.1 mL of the extract to be tested into an Erlenmeyer flask, add 0.2 mL of 10% HCl, and then add 4.7 mL of distilled water and shake well. Measure the OD value multiple times at 243 nm and record the data as A1. Take 0.1 mL of the extract to be tested into an Erlenmeyer flask, add 1.00 mL of distilled water and 0.4 mL of 1 mol / L NaOH and shake well. Let it stand for 20 min, add 0.4 mL of 10% HCl and mix well, then add 3.1 mL of distilled water. Measure the OD value multiple times at 243 nm and record the data as A2. Sample absorbance value = absorbance of the extract to be tested A1 ~ absorbance of the alkaline-treated extract to be tested A2, formula: Vtotal: sample final volume, V1: volume of sample solution taken for absorbance measurement.

[0107] As shown in Table 5, the vitamin C content of the freeze-dried purple cabbage meal replacement cereal bars was 22.05 mg / 100g DW. The vitamin C content of the freeze-dried purple cabbage meal replacement cereal bars obtained by vacuum freeze-drying was higher than that of the single sample. The amount of excipients added and the processing process affected the changes in its nutritional composition.

[0108] (6) Determination of total phenols

[0109] Preparation of sample extract: Weigh 4 mL of glacial acetic acid into a 100 mL volumetric flask and dilute to volume with anhydrous methanol as the sample extractant.

[0110] ①Preparation of sample extract

[0111] Take 1g of each of the two sample powders into a mortar, add 10mL of sample extractant to each, and grind and mix well. Pour the mixture into the corresponding numbered conical flasks. Add another 5mL of sample extractant to each of the other groups. After cleaning the mortar, pour the mixture into the corresponding conical flasks, seal with plastic wrap, and store the mixture at 4℃ for 12 hours. Transfer the mixture into centrifuge tubes, centrifuge at 4000r / min for 15min, collect the supernatant, and pour it into a 25mL conical flask. Dilute to volume with sample extractant to obtain the sample extract.

[0112] ② Construction of standard curves

[0113] Pipette 0.0, 0.125, 0.25, 0.50, 1.00, 1.50, 2.00, and 3.00 mL of 0.5 mg / mL gallic acid standard stock solution into 25 mL amber volumetric flasks, and dilute to the mark with water. Pipette 1 mL of the gallic acid series standard solutions into a 25 mL graduated test tube, add 6 mL of deionized water and 1 mL of L-Lolin-phenol reagent, shake well, and let stand for 6 min. Then add 4 mL of 10.6% sodium carbonate solution, shake well, and let stand at room temperature for 60 min. Dilute to the mark with deionized water and shake well. Measure the absorbance at 760 nm. Plot a gallic acid standard curve with concentration on the x-axis and absorbance on the y-axis. Figure 5 .

[0114] ③ Sample determination

[0115] Dilute the sample extract 10 times, add reagents according to the above standard curve preparation, and measure the absorbance multiple times at 760 nm. Calculate the total phenol concentration in the sample solution based on the standard curve.

[0116] Table 5 shows the total phenol content of freeze-dried purple cabbage meal replacement cereal bars at 75.85 mg / 100g DW. Studies indicate that polyphenols in purple cabbage hydrolyze during high-temperature cooking, resulting in water loss; excessively high temperatures damage cell structure and cell membranes, causing the separation of enzymes and reactants; during low-temperature drying, polyphenol oxidase is not completely inactivated, leading to significant phenolic decomposition; certain trace elements in excipients consume total phenols; and both cooking and vacuum freeze-drying processes cause substantial loss of total phenol content.

[0117] (7) Determination of total anthocyanins

[0118] Buffer preparation: A pH 1.0 buffer solution was prepared by mixing 0.2 mol / L KCl and 0.2 mol / L HCl in a volume ratio of 25:67, and a pH 4.5 buffer solution was prepared using 0.4 mol / L CH3COONa3H2O. 1 mL of each sample extract was transferred to two 10 mL amber volumetric flasks, and the volumes were adjusted to the required levels using the pH 1.0 and pH 4.5 buffer solutions, respectively. After equilibration at low temperature and in the dark for 2 hours, the absorbance (A) of the samples was measured using UV spectrophotometry at wavelengths of 520 nm and 700 nm. Total anthocyanins were calculated using cyanidin-3-glucoside (Cy3G) as the equivalent, and expressed as mg Cy3G / 100g sample.

[0119] Table 5 shows the total anthocyanin content of freeze-dried purple cabbage meal replacement cereal bars at 33 mg Gy3g / 100g. Anthocyanins dissolve in water, and temperature affects their content. Specific heat can activate the cytoplasm of purple cabbage, leading to the release of antioxidants and ultimately forming low-molecular-weight soluble antioxidants. Cooking is the main reason for the decrease in total anthocyanin content. Compared to other drying methods, vacuum freeze-drying causes less damage to anthocyanins, and the retention of total anthocyanins in freeze-dried purple cabbage meal replacement cereal bars is much higher than that of single-ingredient cereals.

[0120] (8) Shelf life prediction study

[0121] To achieve optimal flavor and texture, freeze-dried purple cabbage meal replacement cereal bars are made by combining purple cabbage powder and cereal grains. They have a shelf life of 16 months when stored at 18-20°C. However, freeze-dried purple cabbage meal replacement cereal bars contain a certain amount of moisture, which can accelerate oil oxidation. Oxidation can lead to a rancid taste and safety issues. Furthermore, the main chemical binder in freeze-dried purple cabbage meal replacement cereal bars is malt syrup. Adverse changes in flavor, texture, and structure during storage can severely impact product quality. Therefore, shelf-life prediction studies for freeze-dried purple cabbage meal replacement cereal bars are essential.

[0122] This paper uses conventional PE bags to predict the shelf life of freeze-dried purple cabbage meal replacement cereal bars. Specifically, the freeze-dried purple cabbage meal replacement cereal bars were sealed in PE bags, one small piece per bag, and then stored at room temperature (21–23°C, 40%–50% relative humidity) for a storage test. The acid value and peroxide value of the product under room temperature storage conditions were measured, and the shelf life of the freeze-dried purple cabbage meal replacement cereal bars was predicted in conjunction with changes in sensory quality and microbial growth.

[0123] ① Shelf life prediction using acid value and peroxide value as assessment indicators

[0124] Based on preliminary experiments, the acid value and peroxide value of the product only began to show significant changes after 5 months of shelf life. Therefore, samples were taken at 5, 6, 7, 8, 9, 10, 11, and 12 months of shelf life for acid value and peroxide value testing. Mathematical models were established to predict the shelf life of freeze-dried purple cabbage meal replacement cereal bars at room temperature, using acid value and peroxide value as indicators.

[0125] Acid value determination: Refer to Method I, cold solvent indicator titration, of GB5009.229-2016 "National Food Safety Standard - Determination of Acid Value in Food". Peroxide value determination: Refer to Method I, titration, of GB5009.227-2016 "National Food Safety Standard - Determination of Peroxide Value in Food".

[0126] GB7099-2015, the National Food Safety Standard for Pastries and Bread, stipulates that the acid value of pastry products must not exceed 5 mg / g. The shelf-life prediction results using acid value as a reference indicator are shown below. Figure 6 ,Depend on Figure 6 It is evident that the acid value of freeze-dried purple cabbage meal replacement cereal bars packaged in PE bags tends to increase with longer storage periods. Using acid value as an indicator, the shelf life of puffed Job's tears cereal bars packaged in PE bags is labeled as 9 months.

[0127] In the early stages of food oxidation, unstable peroxides are produced. This process can be characterized by measuring the peroxide value of the product. A higher peroxide value indicates a more severe degree of oxidation. GB7099-2015, the National Food Safety Standard for Pastries and Bread, stipulates that the peroxide value of pastry products must not exceed 0.25 g / 100g. See [link to shelf-life prediction results using peroxide value as a reference indicator]. Figure 7 ,Depend on Figure 7 It can be seen that, based on the peroxide value, the shelf life of freeze-dried purple cabbage meal replacement cereal bars packaged in PE bags is 10 months.

[0128] ② Shelf life prediction using sensory quality scores as a reference indicator

[0129] The acid value and peroxide value only begin to show significant changes after 5 months of storage. Therefore, samples are taken at 5, 6, 7, 8, 9, 10, 11, and 12 months of storage for sensory evaluation. According to the sensory scoring guidelines and preliminary experiments, a sensory score below 50 is considered unqualified. If the sensory score of a product is below 50 in a given month, sensory evaluation will not be conducted again starting the following month.

[0130] Besides acid value and peroxide value, the quality changes of freeze-dried purple cabbage meal replacement cereal bars are also reflected in the deterioration of flavor, taste, and texture. Although these indicators are difficult to measure with instruments or the cost of measurement is too high, these changes are easily perceived by consumers. Therefore, it is necessary to conduct sensory testing on the samples to assess consumers' acceptance of the sample deterioration. As shown in Table 8, the sensory quality of freeze-dried purple cabbage meal replacement cereal bars in PE bags began to fail after 6 months.

[0131] Table 8. Changes in sensory quality of freeze-dried purple cabbage meal replacement cereal bars during room temperature storage.

[0132]

[0133] ③ Shelf life prediction using microorganisms as a reference indicator

[0134] The acid value and peroxide value only begin to change significantly after 5 months of storage. Therefore, samples should be taken at 5, 6, 7, 8, 9, 10, 11 and 12 months of storage to determine the total bacterial count, coliform count and total mold count of the samples.

[0135] Total bacterial count determination: Refer to GB4789.2-2016 "National Food Safety Standard - Microbiological Examination of Food - Determination of Total Bacterial Count". Coliform bacteria determination: Refer to GB4789.3-2016 "National Food Safety Standard - Microbiological Examination of Food - Coliform Count" - Method 1, MPN counting method. Total mold count determination: Refer to GB4789.15~2016 "National Food Safety Standard - Microbiological Examination of Food - Mold and Yeast Count" - Method 1, plate count method.

[0136] The total bacterial count, E. coli, and mold count of the products were tested after being stored for 5, 6, 7, 8, 9, 10, 11, and 12 months, respectively. The test results are shown in Table 9. All results meet the national standard GB7099-2015, which specifies a total bacterial count ≤10⁴ CFU / g, E. coli ≤10 CFU / g, and a total mold count ≤150 CFU / g. Therefore, using microbiological indicators as a reference, the shelf life of the freeze-dried purple cabbage meal replacement cereal bars in PE bags exceeds 12 months.

[0137] Table 9. Changes in sensory quality of freeze-dried purple cabbage meal replacement cereal bars during room temperature storage.

[0138]

[0139] In summary, the predicted shelf life of freeze-dried purple cabbage meal replacement cereal bars packaged in PE bags at room temperature is as follows: 9 months with acid value as a reference indicator; 10 months with peroxide value as a reference indicator; sensory quality assessment results show that the freeze-dried purple cabbage meal replacement cereal bars in PE bags begin to fail the test after 6 months; and based on microbiological indicators, the shelf life of products packaged in PE bags exceeds 12 months. Therefore, considering the shelf life tests based on acid value, peroxide value, sensory scores, and microbiological indicators, the shelf life of products packaged in PE bags at room temperature is 6 months.

[0140] In summary, the freeze-dried purple cabbage meal replacement cereal bars prepared by this invention are ready-to-eat foods made by mixing processed purple cabbage with cooked grains. This not only retains the unique flavor and color of purple cabbage and is rich in anthocyanins, dietary fiber, and various vitamins, resulting in high nutritional value, but also the added grains complement the purple cabbage, making the cereal bars more nutritionally complete. They are convenient to eat and extend the shelf life of the product. They comply with GB7099-2015 "National Food Safety Standard for Pastries and Bread" and GB / T20977-2007 "General Rules for Pastries," contain no allergens, and meet product quality requirements under normal temperature transportation and storage conditions, thus possessing significant economic value.

[0141] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0142] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A freeze-dried purple cabbage meal replacement cereal bar, characterized in that, The ingredients, by weight, include the following components: 30-50 parts purple cabbage powder, 20-30 parts glutinous rice, 30-45 parts rolled oats, 5-16 parts goji berries, 10-20 parts nuts, 5-10 parts white sugar, and 10-20 parts malt syrup.

2. The freeze-dried purple cabbage meal replacement cereal bar according to claim 1, characterized in that, The purple cabbage powder is obtained by grinding freeze-dried purple cabbage slices through an 80-mesh sieve and then passing them through a metal detector. The purple cabbage powder should meet the requirements of being free of foreign matter and odor.

3. The freeze-dried purple cabbage meal replacement cereal bar according to claim 1, characterized in that, The nuts include at least one of walnuts and cashews, and are crushed to a particle size of 0.5 mm to 2 mm.

4. The method for preparing freeze-dried purple cabbage meal replacement cereal bars according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Wash the glutinous rice thoroughly in clean water, drain it, pour it into a pot, add water and cook to obtain raw material A. (2) Pour the oatmeal into a pot and steam it to obtain raw material B. (3) Mix purple cabbage powder with goji berries and nuts to obtain raw material C. (4) Mix white sugar and malt syrup and heat to obtain mixed malt syrup. (5) Add raw materials A, B and C to the mixed maltose syrup and stir evenly to obtain mixture D. (6) After cooling the mixture D, inject it into the mold for pre-freezing and shaping. After pre-freezing, remove the mold and place it in the freeze-drying tray for vacuum freeze-drying. Dry the material until the moisture content is ≤5% to obtain freeze-dried purple cabbage meal replacement cereal strips.

5. The method for preparing freeze-dried purple cabbage meal replacement cereal bars according to claim 4, characterized in that, The cooking conditions for glutinous rice in step (1) are: temperature 85-95℃ and time 40-45min, to obtain raw material A; the cooking temperature for oats in step (2) is 85-95℃ and time is 15-20min, to obtain raw material B.

6. The method for preparing freeze-dried purple cabbage meal replacement cereal bars according to claim 4, characterized in that, In step (4), white sugar and malt syrup are mixed in a ratio of 1:2 and heated to 80-85°C to obtain mixed malt syrup.

7. The method for preparing freeze-dried purple cabbage meal replacement cereal bars according to claim 4, characterized in that: In step (6), cooling is performed by cooling to room temperature in an ice-water mixing zone; the mold dimensions are 5cm×2cm×1.5cm; pre-freezing is performed by pre-freezing at -20℃~-25℃ for 4 hours; demolding is performed by rapid demolding at -18℃; vacuum freeze drying is performed by freezing at -30℃ for 2~3 hours followed by vacuum drying, with cold trap temperature of -35℃~-45℃, vacuum degree ≤100Pa, and partition temperature of 45℃ for 4 hours and 65℃ for 12 hours.

8. A freeze-dried purple cabbage meal replacement cereal bar obtained by the preparation method according to any one of claims 1 to 7.

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